It is very likely that he is responsible. Since the design unit and you personally have collected design fees and labor remuneration, they should provide qualified design documents and assume corresponding responsibilities.

According to Article 19 of the "Construction Project Quality Management Regulations"

Survey and design units must conduct surveys and designs in accordance with mandatory standards for project construction, and ensure the quality of their surveys and designs. Responsible. Registered architects, registered structural engineers and other registered practitioners should sign on the design documents and be responsible for the design documents.

Article 28

The construction unit must construct in accordance with the engineering design drawings and construction technical standards, and may not modify the engineering design without authorization or cut corners. If the construction unit discovers errors in design documents and drawings during the construction process, it shall promptly provide opinions and suggestions.